一、soon after中的 after 可以是连词、介词或副词。所以，soon after 后可接句子、名词（代词、动名词），也可以单独使用。

1.soon after接句子：

He went into hiding soon after the government denounced him.

2.soon after接名词、代词、动名词：

She began to feel dizzy soon after the accident.

Night fell, and soon after that he left.

He took a flier in politics soon after getting his degree.

3.soon after单独作状语：

The family moved to Hardingham in June 1983, and Sarah's first child was born soon after.（句末）

He joined the army in 1914, and soon after was promoted to the rank of captain.（句首）

要注意的是，soon after单独作状语时，相当于soon afterward(主美)或soon fterwards(主英)，且后者更常用。

二、after作为副词，通常要与一些其它的时间副词或名词连用。例如：

He ate lunch and left just / right / immediately / shortly / soon after.

Not long after / afterward, the phone rang.

He returned 20 years after.

但是，即便 20 years after 并没有错，将 after 改为 later 或 afterwards 更为自然、更符合英语习惯。

至于前面没有出现其它表示时间的词语，after 最好不用。例如：

She's having lunch with me, and afterwards (not after) we are going for a walk. (CEED)

注：以上例句均源于现代英文辞书原著，在此不一一列出。